In 756 A.D.
the Italian Papal States (much of the city of Rome and major areas in western Italy) were officially acquired by the Catholic
Church. This land transfer was legitimated on the basis of a document supposedly written by the Roman Emperor Constantine
I in 337 A.D. which granted all of these regions to Pope Sylvester I (Pope from 315-335 A.D.) and his successors.

For
many centuries the authenticity of the Donation of Constantine was not questioned. However, in 1440 Lorenzo Valla published
his Declamitio de falso credita et ementia donatione Constantini (Discourse on the Forgery of the Alleged Donation of Constantine).
In this declamation, Valla argued that the donation was a fraud. He noted that not only was there no record indicating that
Pope Sylvester I had been aware of such a gift, but also that the text of the Donation contained a number of historical anachronisms.
For instance, it referred to Byzantia as a province when in the fourth century it was only a city. It referred to temples
in Rome that did not yet exist; and finally, it referred to 'Judea' which also did not yet exist.

It is now believed
that the Donation of Constantine was actually written around 750 A.D., shortly before the Catholic Church acquired
the Papal States (and long after Constantine's death). Its true author is unknown. The Catholic Church ceded the Papal States
back to Italy in 1929.